<template>
 <div id="sonApp">
   <div class="son">这是显示的son组件：
     <button @click="updateTitle('这是回传给父类的参数')">点击我向父类传递参数</button>
   </div>
 </div>
</template>
<script>
export default {
  props:['title1'],
  methods :{
    updateTitle(msg){
      this.$emit('changeTitle', msg);
    }
  }
}
</script>
<style scoped>
#sonApp div{
  width: 200px;
  height: 200px;
  background-color: red;
}
</style>